2008ApJ...688.1060H

Result. from the ongoing Bulge Radial Velocity Assay (BRAVA) are presented. BRAVA uses M red giant stars, selected from the 2MASS catalog to lie within a bound of reddening-corrected color and luminosity, as targets for the Cerro Tololo Inter-American Observatory 4 m Hydra multiobject spectrograph. Three years of observations investigate the kinematics of the Galactic bulge major (-10°<l<+10°, b=-4°) and minor (-6°<b<+5°, -0.4°<l<0.0°) axes with ∼3300 radial velocities from 32 bulge fields and one disk field. We construct a longitude-velocity plot for the bulge stars and find that, contrary to previous studies, the bulge does not rotate as a solid body; from -4°<l<+4° the rotation curve has a slope of roughly 100 km/s/kpc and flattens considerably at greater l, reaching a maximum rotation of 75 km/s. We compare our rotation curve and velocity dispersion profile both to the self-consistent model of Zhao and to N-body models; neither fits both our observed rotation curve and velocity dispersion profile. We place the bulge on the plot of V_max/σ vs. ε and find that the bulge lies near the oblate rotator line and very close to the parameters of NGC 4565, an edge-on spiral galaxy with a bulge similar to that of the Milky Way. We find that our summed velocity distribution of bulge stars appears to be sampled from a Gaussian distribution, with σ=116±2 km/s for our full data set. Two candidate cold streams are not confirmed with additional data.